- 1). Spray the Potentilla argentea with a chemical or organic herbicide early in the morning on a day when the air is calm, no rain is expected and temperatures are above 50 F. Hold a piece of cardboard in front of nearby plants to protect them from over-spray.
- 2). Spray again in three to four weeks if new growth or new plants emerge. Chemical herbicides, such as glyphosate or 2,4-D, kill the whole weed. Treatment with organic herbicides -- such as vinegar, citrus and oil or ammoniated soap -- weakens the weed by killing the top and must be repeated every three weeks until the weed is dead.
- 3). Hoe the plants off at ground level as early in spring as they emerge. Repeat three or four times -- which will weaken the plant so it can't photosynthesize -- until it dies. Don't let Potentilla argentea bloom and set seed.
- 4). Sprinkle a pre-emergent herbicide on bare ground to prevent seedlings from maturing. Cover unplanted areas with landscape cloth or cardboard. Top with 3 to 4 inches of mulch.